Scots Bay Survey # 7 Results from 29/07/2024
Survey Details
4 commercial purse seiners conducted this fishing survey on 29/07/2024 starting at 21:00:00, which was 1.78 hours after hide tide.
All vessels ran two transects each in the Main Survey Box.
There was a plankton tow and replicate conducted and CTD cast by Lady Janice II.
No tags were applied during this survey.
Samples were obtained for target strength estimation.
Tides Tables
Tide Schedule for Margaretsville NS, Station #315m Source: www.waterlevels.gc.ca
Acoustic Equipment
Each vessel was equipped with a Simrad ES38-18/200-18C combi (2-in-1) transducer prior to the survey that contains a 38kHz split beam and 200 kHz single beam transducer. Data was logged to the computer hard-drive for post-processing. All participating boats were calibrated on 38kHz before the survey.
Survey Results
Main Results
The results are subject to change as DFO will re-evaluate data editing, area estimation and apply a target strength.
Preliminary biomass prediction for Scots Bay using standardized parallel transects is 32,655mt, and with turnover applied 32,016mt.
Transect Details
| Vessel | Transect # | Date/Time Start | Date/Time End | Start Lon | Start Lat | End Lon | End Lat | Location | Distance (km) | Speed |
|---|---|---|---|---|---|---|---|---|---|---|
| BP | T01 | 2024-07-29 19:45:33 | 2024-07-29 22:48:46 | -65.243 | 45.032 | -64.745 | 45.195 | SB | 43.22 | 7.64 |
| BP | T02 | 2024-07-29 23:12:01 | 2024-07-30 01:11:51 | -64.759 | 45.249 | -65.194 | 45.102 | SB | 37.95 | 10.26 |
| FM | T01 | 2024-07-29 21:23:09 | 2024-07-30 00:27:14 | -65.231 | 45.062 | -64.765 | 45.218 | SB | 40.99 | 7.21 |
| FM | T02 | 2024-07-30 00:48:41 | 2024-07-30 02:52:48 | -64.786 | 45.270 | -65.209 | 45.123 | SB | 37.23 | 9.72 |
| LJ | T01 | 2024-07-29 20:22:17 | 2024-07-30 00:02:38 | -65.238 | 45.048 | -64.698 | 45.225 | SB | 46.98 | 6.91 |
| LJ | T02 | 2024-07-30 00:23:08 | 2024-07-30 02:55:43 | -64.755 | 45.265 | -65.233 | 45.103 | SB | 41.69 | 8.85 |
| MS | T01 | 2024-07-29 20:19:15 | 2024-07-30 00:18:01 | -65.234 | 45.076 | -64.725 | 45.245 | SB | 49.32 | 6.69 |
| MS | T02 | 2024-07-30 00:40:59 | 2024-07-30 03:02:32 | -64.787 | 45.284 | -65.201 | 45.141 | SB | 37.69 | 8.63 |
Survey Summary
| Vessel | Transect No. | Target Strength (db/kg) | Mean Sa (/m2) | Biomass Density (kg/m2) |
|---|---|---|---|---|
| BP | T01 | -35.5 | -43.905 | 0.144 |
| FM | T01 | -35.5 | -44.048 | 0.140 |
| LJ | T01 | -35.5 | -44.828 | 0.117 |
| MS | T01 | -35.5 | -46.807 | 0.074 |
| FM | T02 | -35.5 | -53.365 | 0.016 |
| MS | T02 | -35.5 | -54.611 | 0.012 |
| BP | T02 | -35.5 | -54.651 | 0.012 |
| LJ | T02 | -35.5 | -55.223 | 0.011 |
| Note: | ||||
| Transects are listed from greatest to least backscatter. |
| Layer | Target Strength | Area (km2) | Mean Sa | Density (kg/m2) | Biomass (tons) | Percent Area | Percent Biomass | Standard Error (tons) | Standard Error (%) |
|---|---|---|---|---|---|---|---|---|---|
| Main Box | -35.5 | 474 | -47.1194 | 0.0658 | 32,654.99 | 100 | 100 | 10,122.87 | 31 |
Greatest Biomass Densities
A snip from the transect with the greatest biomass density (kg/m2)
The single point with the largest biomass density (kg/m2) was recorded by FM, at the following location:
The transect with the greatest average biomass density (kg/m2) was recorded by BP, at the following location:
Annual Summaries
|
Current Year
|
Previous Year
|
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|---|---|---|---|---|---|---|---|---|---|
| Ground | Survey Number | Survey Date | HSC Estimate | HSC Turnover Adjusted | Survey Date | HSC Estimate | HSC Turnover Adjusted | DFO Estimate | DFO Turnover Adjusted |
| Scots Bay | 1 | 2024-05-05 | 78,662 | 78,662 | 2023-05-22 | 40,856.000 | 40,856 | 47,629 | 47,629 |
| Scots Bay | 2 | 2024-05-20 | 29,842 | 17,255 | 2023-06-06 | 113,767.329 | 108,783 | 98,582 | 92,772 |
| Scots Bay | 3 | 2024-06-02 | 93,804 | 89,523 | 2023-06-18 | 34,279.387 | 15,158 | 29,417 | 12,720 |
| Scots Bay | 4 | 2024-06-16 | 33,347 | 22,278 | 2023-07-02 | 11,744.776 | 5,113 | 9,330 | 3,622 |
| Scots Bay | 5 | 2024-07-01 | 7,252 | 3,123 | 2023-07-16 | 19,282.634 | 17,575 | 17,387 | 16,022 |
| Scots Bay | 6 | 2024-07-15 | 4,539 | 3,560 | 2023-07-30 | 4,549.933 | 1,904 | 3,474 | 1,093 |
| Scots Bay | 7 | 2024-07-29 | 32,655 | 32,016 | 2023-08-13 | 4,298.806 | 3,616 | 2,777 | 2,247 |
| Scots Bay | 9 | NA | NA | NA | 2023-09-10 | 3,053.669 | 2,916 | 3,219 | 0 |
| Scots Bay | 10 | NA | NA | NA | 2023-09-24 | 3,419.932 | 2,997 | 2,318 | 0 |
| Scots Bay | 8 | NA | NA | NA | 2023-08-27 | 2,896.659 | 2,300 | 1,612 | 1,224 |
| Scots Bay | 11 | NA | NA | NA | 2023-10-09 | 3,387.515 | 2,971 | 2,521 | 0 |
| Year | Ground | HSC Estimate | HSC Turnover Adjusted | DFO Estimate | DFO Turnover Adjusted |
|---|---|---|---|---|---|
| 2023 | Scots Bay | 241,536.6 | 204,189 | 218,266 | 177,329 |
| 2024 | Scots Bay | 280,101.0 | 246,417 | NA | NA |
Plankton, and CTD Data
Summary map
Plankton Data
Tow Summary Table
|
Tow 1
|
Tow 2
|
|
|---|---|---|
| Base Details | ||
| Vessel | Lady Janice II | Lady Janice II |
| Set Number | SB2024-11 | SB2024-12 |
| Ground | SB | SB |
| Date | 29/07/2024 | 29/07/2024 |
| Wind Direction (km/h) | W | W |
| Swell (m) | 0.5 | 0.5 |
| Air Temp (c) | 22 | 22 |
| Tow Details | ||
| Tow Start | 19:04:00 | 19:21:00 |
| Tow End | 19:14:00 | 19:31:00 |
| Start Lat | 45.05817 | 45.05200 |
| End Lat | 45.05433 | 45.05283 |
| Start Lon | -65.19433 | -65.20250 |
| End Lon | -65.20217 | -65.21200 |
| Avg Tow Depth (m) | 1.730536 | 1.441772 |
| Speed | NA | NA |
| Heading | NA | NA |
| Tide Direction | against | against |
| Other Data Collection | ||
| Flow Start | 157440 | 199550 |
| Flow End | 199550 | 236886 |
| No. Revolutions | 42110 | 37336 |
| Distance (m) | 1131.622 | 1003.330 |
| Volume | 3554.991 | 3151.962 |
| Secchi Disappear (m) | 7 | 7 |
| Secchi Reappear (m) | 6 | 6 |
Tow Depth Profiles
Plankton tow depth profile #1
Plankton tow depth profile #2
The first tow is SB2024-11, which was against the tide and had an average depth of 1.7305365m. The second tow is SB2024-12, which was against the tide and had an average depth of 1.4417725m.
Captured plankton
Captured plankton from the surface tows
CTD Data
CTD depth profiles for all 2024 Scots Bay surveys so far.
Sea surface temperatures
Annual average sea surface temperatures (SST) for Scots Bay.
Vessel Performance
Speed
Average vessel speed was 8.24. This is above the 8 knot requirement; vessels are urged to slow down to prevent backscatter noise from interfering with the acoustic data.
Distance
More than 2km of distance was cut from the planned lines; vessels are reminded to complete their assigned lines straight and without deviating or cutting corners short.